[Kelly_2000]

"That's obviously true, but based on previous threads people have this vast emotional attachment to the idea that mining asteroids will be economically viable."

I agree the only reason that mining an asteroid would make logical sense, is if someone found a element on one that does not exist on our periodic table or planet.

[agere_contra]

If you mine asteroids and use the minerals in space instead of returning them to earth - e.g. to build other spaceships or solar panels or whatnot - then that would come closer to economic viability. We are talking about Von Neumann style automation here.